Electric fuse.



" I PATENTED 1330.11, 1906. L. B. BUCHANAN;

ELECTRIC FUSE. I

APPLICATION FILED APR. 2. 1906.

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LEONARD s. BUCHANAN, or woeunn, MAss cnusErrs.

EL ECTRlC FUSE.

Specification of Letters Patent.

Patented Dec. 11, 1906,

Application filed April 2, 1906. Serial Nou309,33.

of which is disclosed in Letters Patent No.

801,467, granted to B. S.'.Luthe'r and me, dated October 10, 1905, and may. be used 1n any fuse of the cartridge or inclosed type where a filling material is employed.

' time to the The object of my invention is to provide a fuse the sheath of which will ,be protected. from an excessive rise in temperature, and Whichwill not explode or maintain an are when the fuse-strip is disrupted, and which is not liable to deteriorate by exposure to dampness or la se of time, and which may be made extreme y sensitive so as to fuse with great regularity on exposure for the requisite rescribec overload.

I accomp ish the object of my invention essentially by the use of a new and improved filling material.

Many filling materials have been suggestedfor instance, silicic acid,- slaked lime, plaster-of-paris, sand, ground asbestos, chimney-dust, ashes, slate-dust, calcium carbonate, and magnesium carbonate, all of which have serious defects and operate unsatisfactorily. It is true that the probability of fire or injury to the apparatus by premature or delayed disru tion of the fuse or heating or explosion o the sheath or otherwise may be much reduced or eliminated when the defective filling materials hitherto used are employed by the use of l'usesof larger dimensions than are necessary when my improved fuse is used or by the use of expensive materials to protect the sheath from heat and other devices; but all of these devices add to the expense of the fuse and to the (liflioulty of manufacture and do notmake the fuse less defective in principle, but merely protect the apparatus in circuit with the fuse or the surroundings from the dangerous results of its defects.

Of the filling materials hitherto suggested sand, set" plaster-of-paris, ground asbestos,

slalred lime, and slate-dust are unsatisfactory,

as the sheath heats to too high a temperature and the fuse operates too slowly. The carbonates of lime or magnesium (and unset plaster-of-paris if exposed. to sullicient dampness) do not always prevent the explosion of the fuse. In short, all previous fillings suggested have failed to produce perfect results and it is impossible to tell in advance by any knowledge of the physical and chemical properties of a material thatjt will operate any better or even as well as a filling material as the materials hitherto used.

I have discovered that a filling material which meets all the requirements may be made from infusorial earth. The infusorial earthconsists rincipally of silicio oxid. This is ordinari y mixed with considerable vegetable matter and traces of other substances. Unless the infusorial earth is reasonably free from clay and other nonvolatile elements it shouldbe treated in some manner, as by vw ashing, to eliminate the clay, and b heating or otherwise to drive ofi the volati e materials. This treatment by heat should he at a temperature which will not, change the amorphous condition of silicicoxid. It will then be in a very fine powder and when applied as a filler in the usual wa will make a very satisfactory filling materia Tl use wih this filling material of a moderate quantityof any of the fillin materials now commonly used, .such as salted lime and plaster-of-paris, will not materially injure its operation; but I prefer to use the material alone. i V

Figure 1 shows in side elevation one form 'of electric fuse of the cartridge or inclosed type embodying my invention. Fig. 2 is a longitudinal section of the same, taken on the dotted line 2 2. Fig. 3 is an end view of the fuse.

a re resents the sheath or case of a fuse; b, the ise-wire; c c, the terminals at the ends of the sheath or case; 0 c, the end caps; d, the filling material which embodies my invention; 6 e, asbestos fiber or equivalent material, preferably tightly packed into the ends of the sheath or case; f f, packing rings or washers, and g g disks of paper or equivalent material.

The filling material d is practically, pure si'licic oxid derived from infusorialearth and produced by treatinginfusorial earth in such manner as to substantially eliminate such clay and volatile elements as may be eon tained thenein and not to modify or change the normal amorphous condition of the silioic oxid therein.

Having thus described my invention; What I claim as new, and desire "to secure by Letters Patent, is-

1. A fuse having a filling material consisting ofamorphous silicic o iid, substantially as described.

'2. Aiuse having a filling material oonsist ving of iniusorial' earth from which the clay and volatile elements have been substantially removed, substantially as described.

tile elements have been substantially removed substantially as described.

4. A. having a filling material consisting of incinerated infusorial earth, substantially as described.

5. An inolosed fuse of the. cartridge type having a filling material consisting of inln sorial earth containing substantially only amorphous silioio oxid, substantially as described.

In testii'nony whereof I have signed my naineto this specification in the presence of two subscribing witnesses.

LEONARD B. BUCHANAN.

Witnesses B. J. Norms, H. B. DAVIS. 

